$view = views_get_current_view();

if ($view && !empty($view->args[0])) {
$new_var = $view->args[0];

// Drupal 7: taxonomy_get_term_by_name() still exists but returns an array.
$terms = taxonomy_get_term_by_name($new_var);
$term = FALSE;
if (!empty($terms) && is_array($terms)) {
$term = reset($terms);
}

// Only touch the term if we really have one.
if ($term && isset($term->tid)) {
$tid = $term->tid;
// $desc = 'Themed images for ' . $new_var . ' ' . $term->description;
// Do NOT echo it in a Views PHP area; use it to set a variable instead if needed.
}

$breadcrumb = array(
l(t('Home'), ''),
l(t('Thematic Index'), 'themes/index'),
);
drupal_set_breadcrumb($breadcrumb);
}
?>